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  • Why the data binding in this validation example works in WPF?

    - by MartyIX
    I'm wondering how exactly the XAML sample (MSDN sample) works: <Style x:Key="textBoxInError" TargetType="{x:Type TextBox}"> <Style.Triggers> <Trigger Property="Validation.HasError" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/> </Trigger> </Style.Triggers> </Style> Questions: (Validation.Errors)[0].ErrorContent - Is this code somehow checked by WPF? Because Validation.Errors may be an empty collection and in ordinary C# code this code may throw an exception. If this data-binding returns null for valid input - the null value is then casted to empty string (in a text control for example)? The index 0 corresponds to the first error message. How can I return more error messages from Validate method? Thank you for responses!

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  • Beginners PHP / mySQL question

    - by Reg H
    I'm brand new to PHP & MySQL, and one function I'm creating needs to access a large table or database. I've created the database and it's currently in a MySQL table, which I'm accessing with no problem. The table is 11,000 rows in length, with 8 columns (all text less than 8 characters long) - it's static, and will never change. Without getting too particular, my users will hit a button which will trigger scripts to access the data, say 500 times or more. So in general would it be better practice to include all of this data in a big 'switch' or 'if... then' conditional right in my scripts, rather than opening and accessing the database connection hundreds, or maybe even thousands of times? It just seems like that might be a bottleneck waiting to happen. Thanks!

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  • Can anybody explain the working of following code...?

    - by Siddhi
    Can anybody explain the working of following code...? interface myInterface{} public class Main { public static void main(String[] args) { System.out.println(new myInterface(){public String toString(){return "myInterfacetoString";}}); System.out.println(new myInterface(){public String myFunction(){return "myInterfacemyFunction";}}); } } Output is... myInterfacetoString primitivedemo.Main$2@9304b1 All answers saying that myInterface in println() statement is anonymous class. But as I already declared it as an interface, why does it allow me to create anonymous class of same name....? again...if these are anonymous classes then class main should allow me to give any name to these anonymous classes..But if try to do so..I'm getting compilation error

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  • Normalize database or not? Read only MyISAM table, performance is the main priority (MySQL)

    - by hello
    I'm importing data to a future database that will have one, static MyISAM table (will only be read from). I chose MyISAM because as far as I understand it's faster for my requirements (I'm not very experienced with MySQL / SQL at all). That table will have various columns such as ID, Name, Gender, Phone, Status... and Country, City, Street columns. Now the question is, should I create tables (e.g Country: Country_ID, Country_Name) for the last 3 columns and refer to them in the main table by ID (normalize...[?]), or just store them as VARCHAR in the main table (having duplicates, obviously)? My primary concern is speed - since the table won't be written into, data integrity is not a priority. The only actions will be selecting a specific row or searching for rows that much a certain criteria. Would searching by the Country, City and/or Street columns (and possibly other columns in the same search) be faster if I simply use VARCHAR?

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  • Retain Site Background and Switch Pages?

    - by yar
    I was about to redo a Rails site today using AJAX so that the background could remain in place. Then I thought, "that would be exactly like using frames," and then I thought about SEO consequences and I dropped the idea entirely and took a look around the Web. It turns out that few sites -- except for Google itself, which has the link bar at the top -- are doing this. It doesn't look impossible to do, but it's not exactly easy. Aside from Ajaxing, you have to think about updating the query-string and having SEO-friendly links (that actually don't work, but rather make background requests via Javascript). Will any of the new technologies -- HTML5, perhaps -- solve this problem and allow us to have a Web with background colors (and other static elements) that do not disappear momentarily between page refreshes? On the other hand, why are few devs doing this with current technologies? Is it just not a big deal, too complicated to implement, or....?

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  • Class.getArrayType in Java?

    - by ???
    I use the following trick to get the array type of a specific class: @SuppressWarnings("unchecked") public static <T> Class<T[]> getArrayType(Class<T> componentType) { String arrayClassName = "[L" + componentType.getName() + ";"; try { return (Class<T[]>) Class.forName(arrayClassName); } catch (ClassNotFoundException e) { throw new UnexpectedException("Can't get the array type for " + componentType, e); } } But, is there any more elegant way to get this?

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  • How is this problem usually solved without using sever-side scripting?

    - by cyggi
    Simple problem I have so far always solved via PHP: You have a site with header, menu, footer and content field. Header, menu and footer are usually the same for each page. How do you, without PHP or any other server-side language, have the header, menu and footer data exist only in one file? So that for example you don't have ten sites (like home.html, products.html, about.html, ..) all having a copy of the static header and menu in their html files. Now if you want to change the header you have to change ten files. I hope I made my question clear enough, if not please leave a comment :)

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  • What is "with" used for in PHP?

    - by Jason
    I have come across this line in the eloquent ORM library: return with(new static)->newQuery(); I've never seen "with" used before, and cannot find it in the PHP documentation. I'm guessing "with" is a stop-word in most searches, so I am not even getting close. Never having encountered "with" in many years of programming PHP, I feel like I'm missing out. What does it do? I did come across one passing comment regarding the ORM, that mentioned "with" is no longer needed in PHP-5.4, but that was as much as was said.

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  • Print from cloud print

    - by Saikat
    I have a project in jquery mobile and htmnl5. Now I want to print my page from a android device. I found a code which can print with cloud printing. Code are below. var gadget = new cloudprint.Gadget(); gadget.openPrintDialog(); gadget.setPrintDocument("url", "JPG Image","https://www.google.com/landing/cloudprint/testpage.pdf", ""); But the main problem is that I am unable to use my particular area to be print. Please help me. This example is for a static path like google in the above example. But I want to use my own print area from my code.

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  • iPhone SDK: Keep an image from scrolling with a UIScrollView

    - by Wudstock
    Hi, I've been searching all over for an easy way to do this. Right now I have a UIScrollView setup as my main view. There's an Image on the left and a column of TextFields on the right. When any TextField is tapped, the keyboard comes up and hides the bottom TextField. So I have the ScrollView move up to unhide the bottom TextField. Question #1: Is there a way to have it respond to a specific TextField instead of all of them? Question #2: Is there a way to keep the Image on the left static so it doesn't move with the TextFields? Thanks in advance for any help.

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  • Java Collections.Rotate with an array doesn't work

    - by steve_72
    I have the following java code: import java.util.Arrays; import java.util.Collections; public class Test { public static void main(String[] args) { int[] test = {1,2,3,4,5}; Collections.rotate(Arrays.asList(test), -1); for(int i = 0; i < test.length; i++) { System.out.println(test[i]); } } } I want the array to be rotated, but the output I get is 1 2 3 4 5 Why is this? And is there an alternative solution?

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  • syntax problem crating a method that returns an object (java)

    - by David
    I'm trying to create a method that will sum two timeO objects and return a new TimeO object called sum. Here is the relevant code snippet: public static TimeO add (TimeO t1, TimeO t2) { TimeO sum = new TimeO ; ... } When i try to compile it i get this error message: TimeO.java:15: '(' or '[' expected TimeO sum = new TimeO ; ^ 1 error i cant think of any reason why it would want me to open a set of parenthasies or brackets here but its possible that i dont' quite understand the syntax. Whats going wrong here?

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  • Misunderstanding function pointer - passing it as an argument

    - by Stef
    I want to pass a member function of class A to class B via a function pointer as argument. Please advise whether this road is leading somewhere and help me fill the pothole. #include <iostream> using namespace std; class A{ public: int dosomeA(int x){ cout<< "doing some A to "<<x <<endl; return(0); } }; class B{ public: B(int (*ptr)(int)){ptr(0);}; }; int main() { A a; int (*APtr)(int)=&A::dosomeA; B b(APtr); return 0; } This brilliant piece of code leaves me with the compiler error: cannot convert int (A::*)(int)' toint (*)(int)' in initialization Firstly I want it to compile. Secondly I don't want dosomeA to be STATIC.

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  • Merge 2 Colors to make a tranparent Ovelap?

    - by CrazyJoe
    I have two System.Windows.Media.Color (a and b)and need to get a and put over b to simulate tranparency. to use in my merge method: public static Image Merge(Image a,Image b) { for(int x=0;x < b.Width;x++ ) { for (int y = 0; y < b.Height; y++) { a.SetPixel(x, y, b.GetPixel(x, y)); } } return a; } Help Thank's!!

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  • i have done code so please help

    - by davit-datuashvili
    public class bitap{ public static void main(String[]args){ String text="tbillisi"; String pattern="tbilxiri"; int k=2; int m=pattern.length(); long pattern_mask[]=new long[Character.MAX_VALUE+1]; String result=""; boolean[]R=new boolean[m+1]; long i,d; for (i=0;i<=k;i++){ R[i]=~1; } for (i=0;i if (0==(R[k]& (1< System.out.println(result); } } http://en.wikipedia.org/wiki/Bitap_algorithm from this site

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  • Why StringWriter.ToString return `System.Byte[]` and not the data?

    - by theateist
    UnZipFile method writes the data from inputStream to outputWriter. Why sr.ToString() returns System.Byte[] and not the data? using (var sr = new StringWriter()) { UnZipFile(response.GetResponseStream(), sr); var content = sr.ToString(); } public static void UnZipFile(Stream inputStream, TextWriter outputWriter) { using (var zipStream = new ZipInputStream(inputStream)) { ZipEntry currentEntry; if ((currentEntry = zipStream.GetNextEntry()) != null) { var size = 2048; var data = new byte[size]; while (true) { size = zipStream.Read(data, 0, size); if (size > 0) { outputWriter.Write(data); } else { break; } } } } }

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  • Void pointer cast C++ and GTK

    - by Tarantula
    See this GTK callback function: static gboolean callback(GtkWidget *widget, GdkEventButton *event, gpointer *data) { AnyClass *obj = (AnyClass*) data; // using obj works } (please note the gpointer* on the data). And then the signal is connected using: AnyClass *obj2 = new AnyClass(); gtk_signal_connect(/*GTK params (...)*/, callback, obj2); See that the *AnyClass is going to be cast to gpointer* (void**). In fact, this is working now. The callback prototype in GTK documentation is "gpointer data" and not "gpointer *data" as shown in code, what I want to know is: how this can work ? Is this safe ?

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  • How to set up Node server for production on own machine?

    - by Matt Hintzke
    This must be a pretty basic thing to do, but I cannot find any good guide on how to do it on the internet. I only find how to set up a development environment for Node. I want to be able to forward my R-Pi's port 80 to my Node server, which I want to obviously listen on port 80. How can I close the native port 80 so that I can let me Node server listen on that port. Ultimately, I want to be able to access my pi from any remote location. I know how to set up a static IP and forward the port on my router, but now how do I allow Node into port 80?

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  • Google App Engine: Difficulty with Users API (or maybe just a Python syntax problem)

    - by Rosarch
    I have a simple GAE app that includes a login/logout link. This app is running on the dev server at the moment. The base page handler gets the current user, and creates a login/logout url appropriately. It then puts this information into a _template_data dictionary, for convenience of subclasses. class BasePage(webapp.RequestHandler): _user = users.get_current_user() _login_logout_link = None if _user: _login_logout_link = users.create_logout_url('/') else: _login_logout_link = users.create_login_url('/') _template_data = {} _template_data['login_logout_link'] = _login_logout_link _template_data['user'] = _user def render(self, templateName, templateData): path = os.path.join(os.path.dirname(__file__), 'Static/Templates/%s.html' % templateName) self.response.out.write(template.render(path, templateData)) Here is one such subclass: class MainPage(BasePage): def get(self): self.render('start', self._template_data) The login/logout link is displayed fine, and going to the correct devserver login/logout page. However, it seems to have no effect - the server still seems to think the user is logged out. What am I doing wrong here?

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  • HashMap "WriteOnce" Implementation .. need help

    - by JavaNewbie
    import java.util.*; public class HashMapExample { public static class WriteOnceMap<K, V> extends HashMap<K, V> { public V put(K key, V value) { /* WriteOnceMap is a map that does not allow changing value for a particular key. It means that put() method should throw IllegalArgumentException if the key is already assosiated with some value in the map. Please implement this method to conform to the above description of WriteOnceMap. */ } public void putAll(Map<? extends K, ? extends V> m) { /* Pleaase implement this method to conform to the description of WriteOnceMap above. It should either (1) copy all of the mappings from the specified map to this map or (2) throw IllegalArgumentException and leave this map intact if the parameter already contains some keys from this map. */ } } }

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  • Exception handling pattern

    - by treefrog
    It is a common pattern I see where the error codes associated with an exception are stored as Static final ints. when the exception is created to be thrown, it is constructed with one of these codes along with an error message. This results in the method that is going to catch it having to look at the code and then decide on a course of action. The alternative seems to be- declare a class for EVERY exception error case Is there a middle ground ? what is the recommended method ?

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  • Threading in java vs C#

    - by ffayyaz
    I need a little confirmation over something i am confused at . I know how threads work in java. new DialList(string a , string b).start(); // where DialList is a class public class DialList extends Thread { public DialList(String a, string b) { FilePath = a; ThreadLogFile = b"; } public void run() { // some code to run in different thread } } Now i want to run same code in C# , Shall i put the code which is in run() into a method and do something like Thread t = new Thread (runcsharp); // Kick off a new thread t.Start(); static void runcsharp() { // code } or is there some other way to do it ?

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  • Java using enum with switch statement

    - by MisterSquonk
    I've looked at various Q&As on SO similar to this question but haven't found a solution. What I have is an enum which represents different ways to view a TV Guide... static enum guideView { GUIDE_VIEW_SEVEN_DAY, GUIDE_VIEW_NOW_SHOWING, GUIDE_VIEW_ALL_TIMESLOTS } ...when the user changes the view an event handler receives an int from 0-2 and I'd like to do something like this... // 'which' is an int from 0-2 switch (which) { case NDroid.guideView.GUIDE_VIEW_SEVEN_DAY: ... break; } I'm used to C# enums and select/case statements which would allow something like the above and I know Java does things differently but I just can't make sense of what I need to do. Am I going to have to resort to if statements? There will likely only ever be 3 choices so I could do it but I wondered how it could be done with switch-case in Java.

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  • Data structure name: combination array/linked list

    - by me_and
    I have come up with a data structure that combines some of the advantages of linked lists with some of the advantages of fixed-size arrays. It seems very obvious to me, and so I'd expect someone to have thought of it and named it already. Does anyone know what this is called: Take a small fixed-size array. If the number of elements you want to put in your array is greater than the size of the array, add a new array and whatever pointers you like between the old and the new. Thus you have: Static array ————————————————————————— |1|2|3|4|5|6|7|8|9|a|b|c| ————————————————————————— Linked list ———— ———— ———— ———— ———— |1|*->|2|*->|3|*->|4|*->|5|*->NULL ———— ———— ———— ———— ———— My thing: ———————————— ———————————— |1|2|3|4|5|*->|6|7|8|9|a|*->NULL ———————————— ————————————

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  • Exception in C#

    - by user1803513
    I am facing null pointer exception in below code as it is happening very rarely and I tried to debug to replicate the issue but no luck. Can anybody help me what can cause null point exception here. private static void MyTaskCompletedCallback(IAsyncResult res) { var worker = (AsyncErrorDelegate)((AsyncResult)res).AsyncDelegate; var async = (AsyncOperation)asyncResult.AsyncState; worker.EndInvoke(res); lock (IsAsyncOpOccuring) { IsBusy = false; } var completedArgs = new AsyncCompletedEventArgs(null, false, null); async.PostOperationCompleted(e => OnTaskCompleted((AsyncCompletedEventArgs)e), completedArgs); } Null Pointer exception is reported at var async = (AsyncOperation)asyncResult.AsyncState;

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